The technique of somatic cell hybridization has proved to be a valuable tool for genetic analyses of mammalian cells in culture. The overall objectives of the research project are to develop new selective methods for the isolation of somatic cell hybrids which will then be used for (1) mapping human genes, (2) studying the regulation of gene expression and (3) studying the mechanism of herpes viral transformation of mammalian cells. The selective markers are deoxycytidine deaminase (dCD), adenosine kinase (AK) and adenosine deaminase (AD). I have obtained a human-mouse hybrid line selected for human dCD and derived dCD sublines from the original dCD ion hybrid. The human chromosome which carries the dCD gene will be identified by detailed karyotype analyses of the dCD- and dCD ion hybrid lines using modern chromosome banding techniques. Mutant mouse fibroblasts lacking AK and AD have been derived from mouse fibroblasts 3T6. New human-mouse hybrid lines will be prepared using AK and AD as selective markers. These hybrid lines will be analyzed for isozyme patterns of selected enzymes and karyotypes. I will perform herpes viral transformation experiments using the mouse mutant cells deficient in deoxycytidine kinase (dCK) and dCD. These mutant cells will be infected with Herpes simplex virus type I to detect whether these enzyme activities are induced by the virus. If the results are positive, I will transform the mutant cells with UV- inactivated virus and isolate the dCK ion or dCD ion transformants in appropriate selective media. In addition to their use in genetic experiments by somatic cell hybridization, the mouse mutants deficient in AK and AD can be used as model systems for studying two human diseases: hereditary hyperuricennia (gout) and a primary immunodeficiency disease. Studies on gene transfer mediated by Herpes simplex virus could elucidate the mechanisms by which some oncogenic strains of Herpes virus cause malignant transformation of mammalian cells.